Add `--dry-run` to `uv pip uninstall` (#9557)
## Summary
This proposes adding the command line option `uv pip uninstall --dry-run
...`, complementing the existing `uv pip install --dry-run ...` added
for #1244 in #1436.
This option does not exist in PyPA's `pip uninstall`, if adopted it
would be unique to `uv pip`. The code should be considered PoC, it is
baby's first Rust.
The initial motivation was while investigating
https://github.com/moreati/ansible-uv/issues/2 - to allow Ansible module
`moreati.uv.pip` to work with`state: absent` in "check_mode" (Ansible's
equivalent of a dry run), without requiring `packaging` or `setuptools`.
## Test Plan
One new unit test has been added. I pedge to add more if the feature is
desired/accepted
Example usage
```console
➜ uv git:(pip-uninstall--dry-run) rm -rf .venv
➜ uv git:(pip-uninstall--dry-run) ./target/debug/uv venv
Using CPython 3.13.0
Creating virtual environment at: .venv
Activate with: source .venv/bin/activate
➜ uv git:(pip-uninstall--dry-run) ./target/debug/uv pip install httpx
Resolved 7 packages in 178ms
Prepared 5 packages in 60ms
Installed 7 packages in 15ms
+ anyio==4.6.2.post1
+ certifi==2024.8.30
+ h11==0.14.0
+ httpcore==1.0.7
+ httpx==0.28.0
+ idna==3.10
+ sniffio==1.3.1
➜ uv git:(pip-uninstall--dry-run) ./target/debug/uv pip uninstall --dry-run httpx
Would uninstall 1 package
- httpx==0.28.0
➜ uv git:(pip-uninstall--dry-run) ./target/debug/uv pip list
Package Version
-------- -----------
anyio 4.6.2.post1
certifi 2024.8.30
h11 0.14.0
httpcore 1.0.7
httpx 0.28.0
idna 3.10
sniffio 1.3.1
```
---------
Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>
